Polyalkylene oxide having unsaturated groups at chain ends is cured alone to be used as an elastomeric material, or blended with other polymer as a modifier to improve a cross linking property of other polymer. In addition, when the unsaturated group is converted to other more active group such as a silyl group having a hydrolyzable group, polyalkylene oxide can be used as a liquid telechelic polymer which is cured to give an elastomeric material (cf. U.S. Pat. No. 3,971,751).
A conventional method for introducing the unsaturated groups at both chain ends comprises reacting hydroxyl groups of polyalkylene oxide prepared by conventional anionic polymerization with an alkali metal hydroxide (e.g. potassium hydroxide and sodium hydroxide), sodium methoxide or metal sodium to form alkoxide end groups, and then reacting the alkoxide end groups with an active halogen-containing compound having an unsaturated group to produce polyalkylene oxide having unsaturated end groups (cf. U.S. Pat. No. 3,951,888). When propylene oxide as alkylene oxide is polymerized by a conventional anionic polymerization method utilizing potassium hydroxide as a catalyst, it is difficult to produce a polymer having a molecular weight of 3,000 or more and the polymer has a wider distribution of molecular weight, since growing chain ends proceed a chain transfer reaction with propylene oxide monomers.
When polyalkylene oxide is utilized as an elastomeric material, preferably, its molecular weight should controlled to obtain the polymer having desired tensile properties. For example, for the preparation of the elastomeric material having larger elongation, it is necessary to use polyalkylene oxide having a higher molecular weight. To produce polyalkylene oxide having good tensile properties, it is also important for the polymer to have narrow distribution of molecular weight.
It was proposed to react the hydroxyl end groups of two molecules of polyalkylene oxide to elongate the chain length so as to produce polyalkylene oxide having unsaturated end groups with a molecular weight not smaller than 3,000 (cf. U.S. Pat. No. 3,951,881). However, such procedures are troublesome since it is difficult to precisely control the molecular weight. Even by such procedures, it is difficult to produce the polymer having a narrow distribution of molecular weight.
The present inventors have already developed a process for preparing polyalkylene oxide having unsaturated groups at chain ends (cf. Japanese Patent Application Nos. 58745/1985 and 60221/1985). This process utilizes a living polymerization of alkylene oxide in the presence of a complex catalyst prepared by reacting an organoaluminum compound with a porphyrin compound (cf. Makromol. Chem., 182, 1073-1079 (1981)). An example of the porphyrin compound is represented by the formula: ##STR1## wherein R.sup.1 is, the same or different, a hydrogen atom or a C.sub.1 -C.sub.4 alkyl group; and R.sup.2 is, the same or different, a hydrogen atom or a C.sub.1 -C.sub.10 hydrocarbon group. An example of the complex catalyst is represented by the formula: ##STR2## wherein R.sup.1 and R.sup.2 are the same as defined above, and X is a hydrogen atom, a halogen atom or a C.sub.1 -C.sub.4 alkyl group.
The reaction scheme of this process may be as follows: ##STR3## wherein ##STR4## represents the complex (II), and n is an positive integer.
By this process, it is possible to freely control the molecular weight of polyalkylene oxide. Furthermore, polyalkylene oxide produced by this process has narrow distribution of molecular weight. However, polyalkylene oxide produced by this process is fairly expansive since only one mole of polyalkylene oxide is produced per mole of the expensive complex catalyst (II). Therefore, it is highly desired to produce less expensive polyalkylene oxide having an unsaturated end group(s), a high molecular weight and narrow distribution of molecular weight.